[PATCH v3 3/4] dtc: Add /./

Allow constructing new values for a property using old property values.
Can be used to append, pre-append, duplicate, etc.

In practice, it looks as follows:

/dts-v1/;

/ {
	str-prop = "0";
	int-prop = <0>;
};

/ {
	str-prop = /./, "1", /./;
	int-prop = /./, <1>, /./;
};

dts to source output with -T -T also works as expected:

/dts-v1/;

/ { /* temp/a.dts:3:3-6:3, temp/a.dts:8:3-11:3 */
	str-prop = "0", "1", "0"; /* temp/a.dts:4:5-4:20, temp/a.dts:9:5-9:30 */
	int-prop = <0x00>, <0x01>, <0x00>; /* temp/a.dts:5:5-5:20, temp/a.dts:10:5-10:30 */
}; /* temp/a.dts:3:3-6:3, temp/a.dts:8:3-11:3 */

Signed-off-by: Ayush Singh <[email protected]>
---
 dtc-lexer.l  |  5 +++++
 dtc-parser.y |  5 +++++
 dtc.h        |  1 +
 livetree.c   | 23 +++++++++++++++++++++--
 4 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/dtc-lexer.l b/dtc-lexer.l
index de60a70b6bdbcb5ae4336ea4171ad6f645e91b36..7ad98b3c5d1fa24dda04731a64d18ecc6ec1e448 100644
--- a/dtc-lexer.l
+++ b/dtc-lexer.l
@@ -144,6 +144,11 @@ static void PRINTF(1, 2) lexical_error(const char *fmt, ...);
 			return DT_OMIT_NO_REF;
 		}
 
+<*>"/./" {
+			DPRINT("Keyword: /./\n");
+			return DT_PREV_VALUE;
+		}
+
 <*>{LABEL}:	{
 			DPRINT("Label: %s\n", yytext);
 			yylval.labelref = xstrdup(yytext);
diff --git a/dtc-parser.y b/dtc-parser.y
index 4d5eece526243460203157464e3cd75f781e50e7..0b7932d4172f30f1c45a9f521dc43a2fae1692b8 100644
--- a/dtc-parser.y
+++ b/dtc-parser.y
@@ -57,6 +57,7 @@ static bool is_ref_relative(const char *ref)
 %token DT_LSHIFT DT_RSHIFT DT_LE DT_GE DT_EQ DT_NE DT_AND DT_OR
 %token DT_BITS
 %token DT_DEL_PROP
+%token DT_PREV_VALUE
 %token DT_DEL_NODE
 %token DT_OMIT_NO_REF
 %token <propnodename> DT_PROPNODENAME
@@ -308,6 +309,10 @@ propdata:
 		{
 			$$ = data_merge($1, $2);
 		}
+        | propdataprefix DT_PREV_VALUE
+                {
+                        $$ = data_add_marker($1, PREV_VALUE, NULL);
+                }
 	| propdataprefix arrayprefix '>'
 		{
 			$$ = data_merge($1, $2.data);
diff --git a/dtc.h b/dtc.h
index 3a220b9afc99f92ea57d50d348eb0872bc779818..f9bdf1d117f8a70d168243129db8f8d940de8064 100644
--- a/dtc.h
+++ b/dtc.h
@@ -110,6 +110,7 @@ enum markertype {
 	REF_PHANDLE,
 	REF_PATH,
 	LABEL,
+	PREV_VALUE,
 	TYPE_UINT8,
 	TYPE_UINT16,
 	TYPE_UINT32,
diff --git a/livetree.c b/livetree.c
index d51d05830b181476ddbab878ef8b556230b58e2b..11c40724c7a8c8b429230f211455f7bcbdc050ec 100644
--- a/livetree.c
+++ b/livetree.c
@@ -143,6 +143,7 @@ struct node *merge_nodes(struct node *old_node, struct node *new_node)
 {
 	struct property *new_prop, *old_prop;
 	struct node *new_child, *old_child;
+	struct marker *marker;
 	struct label *l;
 
 	old_node->deleted = 0;
@@ -154,6 +155,8 @@ struct node *merge_nodes(struct node *old_node, struct node *new_node)
 	/* Move properties from the new node to the old node.  If there
 	 * is a collision, replace the old value with the new */
 	while (new_node->proplist) {
+		bool prev_value_used = false;
+
 		/* Pop the property off the list */
 		new_prop = new_node->proplist;
 		new_node->proplist = new_prop->next;
@@ -172,10 +175,26 @@ struct node *merge_nodes(struct node *old_node, struct node *new_node)
 				for_each_label_withdel(new_prop->labels, l)
 					add_label(&old_prop->labels, l->label);
 
+				marker = new_prop->val.markers;
+				for_each_marker_of_type(marker, PREV_VALUE) {
+					new_prop->val = data_insert_data(
+						new_prop->val, marker,
+						old_prop->val);
+					prev_value_used = true;
+				}
+
 				old_prop->val = new_prop->val;
 				old_prop->deleted = 0;
-				srcpos_free(old_prop->srcpos);
-				old_prop->srcpos = new_prop->srcpos;
+
+				if (prev_value_used) {
+					old_prop->srcpos =
+						srcpos_extend(old_prop->srcpos,
+							      new_prop->srcpos);
+				} else {
+					srcpos_free(old_prop->srcpos);
+					old_prop->srcpos = new_prop->srcpos;
+				}
+
 				free(new_prop);
 				new_prop = NULL;
 				break;

-- 
2.49.0